Visual Acuity Screening in North Indian Schools: Testing Accuracy and Cost of Alternate Screening Models

Figures & data

Figure 1. Selection process of schools for the study [original].

Figure 2. Teacher training, screening, and diagnosis process [original].

Table 1. Demographics details of students screened, across the three types of primary screeners [original].

		All Class Teachers (ACTs)		Selected Teachers (STs)		Vision Technicians (VTs)
		N (%)	95% CI	N (%)	95% CI	N (%)	95% CI
School Student Strength		3410		2999		3071
Age Group	5–10 years	1551 (45.5)	(43–48)	1269 (42.3)	(39.8–44.8)	1240 (40.4)	(37.9–42.8)
	11–17 years	1859 (54.5)	(52–57)	1730 (57.7)	(55.2–60.2)	1831 (59.6)	(57.2–62.1)
Sex	Male	1950 (57.2)	(54.7–59.7)	1639 (54.7)	(52.1–57.2)	1783 (58.1)	(55.6–60.5)
	Female	1460 (42.8)	(40.3–45.3)	1360 (45.3)	(42.8–47.9)	1288 (41.9)	(39.5–44.4)

Table 2. Screening and referral parameters across the three primary examiners [original].

	ACTs	STs	VTs	p-value (Chi-square)
Total screened	3410	2999	3071
Screened Positive by Screeners (for vision deficit)	214	349	207
Screened other pathology by Screener	39	20	12
Total Referred	253	369	219
Screened Positive Percentage (For Vision deficit)	6.3%	11.6%	6.7%	<0.001
True Positive screened by teachers (for vision deficit)	91	105	168
True Negative screened by teachers (for vision deficit)	3034	2518	2852
False Positive screened by teachers (vision deficit)	123	244	39
False Negative screened by teachers (vision deficit)	162	132	12
Sensitivity (%) (for vision deficit)	36.0%	44.3%	93.3%	<0.001
Specificity (%) (for vision deficit)	96.1%	91.2%	98.7%	<0.001
Positive Predictive Value (%) (for vision deficit)	42.5%	30.1%	81.2%	<0.001
Negative Prediction Value (%) (for vision deficit)	94.9%	95.0%	99.6%	<0.001
Referred to Hospital for Further Examination	70 (2.1)	106 (3.5)	62 (2.0)	<0.001*
Student Compliance Rate for Hospital Referrals	28 (40)	47 (44.3)	20 (32.3)	0.3

*p-value less than 0.05 thus significant.

Table 3. Cost details of screening conducted across three primary screeners [original].

	ACTs	STs	VTs
Total Number of Children Screened	3410	2999	3071
Cost of Screening a Child ($)	0.25	0.20	0.15
Total Cost of Screening ($)	850.47	607.68	473.76
True Positive (for Vision deficit)	91	105	168
Cost per case (identification of Poor Vision) ($)	9.35	5.79	2.82

Data availability statement

Raw data were generated at Dr. Shroff’s Charity Eye Hospital. Derived data supporting the findings of this study are available from the corresponding author [Priya] on request.